JPS6022330B2 - Recording device using multiple semiconductor lasers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording device using a plurality of semiconductor lasers in a light source section.

It goes without saying that a recording medium suitable for recording using a semiconductor laser uses a material that can sufficiently absorb semiconductor laser light. The wavelength of semiconductor laser light is currently 0.
8 to 0.9 Because it is in the near-infrared region of the enemy, photosensitive materials sensitive to ultraviolet or near-ultraviolet visible light, such as diazo, photoresist, and vesicular type photosensitive materials, cannot be recorded by semiconductor lasers. Not suitable. Heat mode type sensitive materials, in which a light-absorbing thin film layer such as Bi is formed on a film base, and holes are formed thermally in this layer using laser energy, are not suitable for semiconductor laser recording in terms of wavelength sensitivity. most suitable. However, at present, the energy sensitivity of this photosensitive material is about 1 pm, and by irradiating the surface of the photosensitive material with a semiconductor laser beam with a peak power of 3 hp for a period of about 30 msec, it is possible to obtain energy sensitivity of 2 pm. It is only possible to make a small hole. Further, such pulse operation is limited by the life span or repetition durability of the semiconductor laser, and currently the maximum duty cycle is 5%. Under these conditions, if 2〃◇ picture elements are arranged 2100 dots vertically and 2970 dots horizontally, and one page is formed by about 1 dot picture element as a whole, The recording time is approximately 79 seconds. This slow recording speed is due to the fact that this recording system does not require post-processing such as developing and fixing, and has the advantage of allowing information to be added later. This is considered to be the biggest reason why the system is not being utilized.

The present invention aims to improve the above-mentioned drawbacks,
To provide a recording device capable of recording at zero high speed even when a semiconductor laser is used as a light source.

The present invention provides a recording device that can perform high-speed recording even when a semiconductor laser is used in combination with a low-sensitivity heat mode member as a recording medium.

In the recording apparatus according to the present invention, a plurality of semiconductor lasers are provided in a light source section, and a scanning surface is simultaneously scanned with a plurality of beams from the light source section.

That is, by simultaneously scanning a scanning surface with a plurality of scanning lines, an attempt is made to overcome the slow recording speed caused by the absolute lack of power of the semiconductor laser. A recording apparatus according to the present invention includes a light source section having a plurality of semiconductor lasers, a deflector for deflecting the plurality of beams from the light source section, a scanning surface scanned by the plurality of beams from the deflector, and a scanning surface scanned by the plurality of beams from the deflector. It is equipped with an imaging optical system that images a beam from a semiconductor laser as a scanning spot on a scanning surface, and scans the scanning surface with a plurality of scanning spots.

In the recording device according to the present invention, an optical element that guides a plurality of beams from the light source section and forms a secondary light source of a desired shape is provided between the light source section and the deflector of the recording device. ,
By arranging this secondary light source at a position with respect to the imaging optical system that is substantially optically conjugate with the scanning plane, alignment of the optical system is facilitated.

This optical element includes an imaging optical system consisting of different lens systems, or a waveguide system that does not have an imaging function but guides the light beam.

Examples of this waveguide include optical thin film circuits and optical fibers. The secondary light source formed by this optical element is usually formed closely in a straight line, and is aligned with the arrangement direction of the image of the secondary light source formed on the scanning plane by the above-mentioned imaging optical system, and on the scanning plane of the image. The scanning direction of the image has a certain angle.

This angle is determined, for example, by the speed of the beam that scans the scanning surface with a spot and the moving speed of the scanning surface, and by appropriately selecting this angle, two-dimensional scanning can be performed effectively. The secondary light source is composed of a plurality of micro light sources corresponding to the semiconductor laser of the light source section, and each micro light source preferably has a shape that has no longitudinal direction or transverse direction in its cross section.

In order to convert the slit-shaped light emitting surface of a semiconductor laser into a minute light source with such a shape, if the above-mentioned optical element is a waveguide, the cross-sectional shape of the waveguide must be relatively easily changed along the light transmission direction. Therefore, the cross-sectional shape can be easily changed. Further, when the optical system is an imaging optical system such as a lens, a minute light source having the above-mentioned shape can be obtained by disposing an anamorphic optical element in the imaging optical system. Hereinafter, the present invention will be explained in detail with reference to Examples. FIG. 1 is a schematic diagram showing an embodiment of the apparatus according to the present invention.

In FIG. 1, a plurality of semiconductor lasers 1 are arranged in isolation, each of which is optically connected to the above-mentioned optical waveguide. The optical connection shown in FIG. 1 is one in which the end face of the waveguide 2 is brought directly into close contact with the semiconductor laser 1, but as will be described later, a lens system or other appropriate device is used to connect the semiconductor laser 1 and the optical waveguide. They may also be connected through a butterfly material. The optical east-emitting ends 3 of the optical waveguide, which are not connected to the semiconductor laser, are arranged in close proximity to each other in a substantially straight line, as shown by 3' when the end face is viewed from the front.

The semiconductor laser 1 and the optical waveguide are monolithically or hybridly formed on a common substrate 4, forming an optical integrated body as a whole. In this case, the effective maximum width of the cross section of the optical waveguide is 5 to 50A. these 5
If it is less than a mountain surface, it is too thin and difficult to process, and if it is more than 50 mountain surfaces, it cannot be effectively reduced with little energy loss. However, there is no essential limit to the upper limit of the thickness, which may be used with a wider cross section that matches the emission area of the laser. Divergent light L from the light output end 3 of the optical waveguide, which serves as the secondary light source of the semiconductor laser, is converted into parallel light L2 by the collimator lens 5, and then enters the galvanometer mirror 7, which is vibrated by the galvanometer 6.

The parallel light beam L3, which has been deflected and scanned by the vibration of the galvanometer mirror, is imaged as a scanning spot 11 on the scanning surface 9 by the scanning imaging lens 8. This scanning surface 9 is a heat mode sensitive material that is compatible with the light beam of the semiconductor laser. Second
The figure shows the scanning plane 9 viewed from the front.
, move in the direction. On the other hand, since the scanning surface moves in the horizontal direction, two-dimensional scanning of the scanning surface is performed. The scanning plane 9
Above is an image 1 of the light east-emitting end 3 of the waveguide as shown in FIG.
0 is imaged. The scanning spots 11 that scan the scanning plane 9 are therefore images of the ends 3 of each waveguide 2, so that the number of scanning spots corresponds to the number of waveguides. The image 10 of the weave 3 is formed such that the arrangement direction of the scanning spots 11 and the scanning direction A of the scanning spots are not perpendicular to each other, but intersect at a certain angle. Therefore, when the galvanometer mirror vibrates, the scanning spot 11 is
, so that the same number of lines as the number of scanning spots are simultaneously scanned. The size of the scanning spots 11 on this scanning surface 9 and the spacing between the spots are as follows:
It can be freely selected depending on the closeness of the waveguide at the end 3, the cross-sectional branch of the waveguide phosphor at the end 3, and the imaging magnification of the scanning optical system.

For example, the size of the scanning spot can be reduced by reducing the size of the cross-section mirror at the end 3 of the waveguide or by reducing the imaging magnification of the imaging lens system. In addition, when the beam from the deflector swings at a constant speed, the scanning imaging lens 8 converts the caravan at the speed of light, which is imaged by the imaging lens, to h,
Assuming that the angle between the light beam incident on the lens and the optical axis is 0, and the focal length of the imaging lens is f, then a lens having the characteristic h=f·0 is used as the imaging lens for scanning.

Furthermore, if the angle 0 of the beam from the deflector entering the imaging lens 8 changes sinusoidally over time, h=f・ar
A lens having characteristics of csina is used. Note that the light output end face 3 of the optical waveguide 2 is connected to the end face 3 of the optical waveguide 2 as shown in FIGS. The end surfaces of the substrates 4 must be aligned, or the end surfaces 3 of the optical waveguides 2 must be provided so as to protrude beyond the substrate 4.

One method of aligning the end face 3 of the optical waveguide 2 and the end face of the substrate 4 is to optically polish both end faces at the same time. As shown in FIG. 3, the thickness of the optical waveguide increases as it approaches the light output end 3, and its cross section has a shape with almost no distinction between the longitudinal direction and the transverse direction. Therefore, since the divergence angle of the light beam from the end 3 is approximately isotropic, a normal spherical lens system can be used as an optical system for imaging the beam from the end 3. There are various methods for forming the above-described optical integrated body consisting of a semiconductor laser and an optical waveguide. For example, a monolithic structure is constructed as follows. An n-GaAs crystal is used as a common substrate, and a multilayer epitaxial layer made of, for example, p-Ga$ sandwiched with GaNAs is formed thereon.

The p-GaAs layer becomes a so-called double heterojunction active layer. For example, the GaAIAs layer has a Ga to AI ratio of 0.8:0.2, 0.93:0.07, 0.7:0.
．． A multilayer structure with a ratio such as 3 may also be used. For example, Ga
o. 93 mountains o. o7As layer and G too. 7AIo. When we used photolithography technology to form a periodic concave-convex shape between the 3As and the 3As layer, a part of the light propagating through the active layer was fed back in the opposite direction by this diffraction grating, and then fed back again. The light is
Since the light is fed back in the opposite direction, the light travels back and forth within the active layer, forming an optical resonator and becoming a laser.
That is, a commonly known distributed feedback laser or distributed Bragg reflector laser is formed. Since these lasers do not require the formation of a reflective end face, they are suitable for monolithic optical curtains. Of course, the reflective end face may be formed by a method such as mechanical corrosion or chemical corrosion, without relying on the diffraction grating method. For example, p-G may be applied to areas on the n-GaAs substrate where no laser is formed or where the laser layer has been removed by etching. 7NO. 3As and undoped G~9No. , a false double layer is epitaxially grown, and this layer of undoped GaNAs can be used as an optical waveguide to propagate laser light.

The laser beam may be divided into multiple lasers by grooves or simply by forming spaced apart electrodes to create multiple lasers that can be driven independently.

Moreover, the thickness of the optical waveguide is usually several meters, which is easy to form.

This method does not use an epitaxial growth layer as described above, but by digging deeply into the n-GaAs substrate in advance.
A thin layer with a low refractive index may be formed to a thickness of lAm or more, and a thin layer with a high refractive index may be further formed thereon. The low refractive index layer is for preventing light from escaping from the waveguide, and for this purpose it is necessary to have a thickness of at least 1Am or more. Low refractive index and high refractive index are relative relationships, and dielectric materials such as various oxides and fluorides that are normally used in antireflection films for lenses etc. are suitable as materials for forming these layers. There is. MgF2, CaF2, N203, Si○
, Si02, Ti02, Zr203, ZnS, etc.

Such an optical waveguide layer is processed by photolithography technology or the like into a corresponding waveguide shape as shown in FIG. 1 in order to guide light from a plurality of semiconductor lasers that can be driven independently.

On the radiation end face of the waveguide, it is desirable to place the waveguides as close to each other as possible from the point of view of recording density. In order to prevent this, at least 1 mound or more, preferably 2 mound or more, and for ease of processing, etc.
It is necessary to provide an interval of ~5 mm.

When considering ease of processing and mass production, the monolithic type as described above is preferable, but when manufacturing small quantities, the following hybrid type is also possible.
For example, as shown in FIG. 4, a laser light source section 12 and an optical waveguide section 13 are made separately, and then they are combined and integrated. The optical waveguide can also be formed by forming a waveguide groove in the substrate in advance and embedding the waveguide in the groove.

The optical waveguide can also be formed by cutting a plastic film into the shape of a waveguide and attaching it to a substrate.

With the advancement of integrated circuits, it is now possible to integrate tens to hundreds of semiconductor lasers and optical waveguides. Next, a case will be described in which the light source section and the optical waveguide are spatially separated, and the light beam section and the optical waveguide are coupled using an optical element.

The light source device shown in FIG. 5 includes a light source section 12 of a semiconductor laser.
An optical fiber 15 fixed on a substrate 14 as an optical waveguide is connected by an imaging lens 16.

For this imaging lens 16, an anamorphic imaging optical system may be used in consideration of the shape of the light emitting part of the semiconductor laser. In this embodiment, the output surface 17 of the optical waveguide 15 is provided to protrude from the edge of the substrate 14 so that the output light is not eclipsed at the edge of the substrate 14. FIG. 6 shows a light source Hishitaka having the same basic structure as the light source Hishitaka shown in FIG. 5, but the difference is that one imaging lens 18 is used instead.

In this light source device, the light output surfaces of the semiconductor lasers and the input end surfaces of the optical waveguides that form each pair are provided at positions that are optically conjugate with respect to the imaging lens 18. That is, the light output surface la of the semiconductor laser and the light input end surface 15a of the optical fiber, similarly lb and 15b, and lc and 15c.
, ld and 15d. le and 15e are provided at optically conjugate positions with respect to the imaging lens 18. In the case shown in Figures 5 and 6, in which the light source part and the optical waveguide are connected using an optical element such as a lens, an anamorphic optical system is used to correct the shape of the light emitting part of the semiconductor laser. By using the waveguide or changing the cross-sectional shape of the waveguide, it is possible to obtain a secondary light source in which there is almost no distinction between the longitudinal direction and the transverse direction of the cross section.

In the case of a semiconductor laser, by directly applying a recording signal to the semiconductor laser, a beam corresponding to the applied signal can be extracted from the semiconductor laser.

Therefore, when recording is performed simultaneously using a plurality of semiconductor lasers as described above, a signal corresponding to each recording signal is simultaneously applied to each semiconductor laser.
FIG. 7 is a perspective view showing a schematic diagram of another embodiment of the device according to the invention.

In FIG. 7, 21 is a semiconductor laser la, lb, l.
A light source section 22 in which a plurality of c, . . . Here, this condensing system 23 will be explained in detail. As shown in FIG. 8, the semiconductor laser 1 has different divergence angles in the orthogonal planes as described above. Therefore, the semiconductor laser 1 has different generation points IQ,
18, these light emitting points IQ, 18 are made to coincide with a certain point P by the condensing system 23. Moreover, the arrangement is such that the light emitted from the semiconductor laser 1 is emitted from the point P in the same direction. Figures 9, 10 and 11
The figures show respective embodiments of the light condensing system 23. In FIG. 9, the condensing system 23 is a positive spherical lens 23a.
The system is composed of a negative cylindrical lens 23b, and the cylindrical lens 23b is a light emitting point IQ.
It has no refractive power against the light east. In Fig. 10, a light emitting point in one direction is matched with a point P by a negative cylindrical lens 23d, and a light emitting point in a direction perpendicular to the negative cylindrical lens 23d is matched with a fiber 23c whose cross-sectional refractive index distribution changes continuously in one direction. It is something. Figure 11 shows a fiber 23e whose cross-sectional refractive index distribution changes in different states in the orthogonal direction, and the light emitting points IQ, 13 that differ in the orthogonal direction.
are made to coincide with the same P point. The light emitted from such a condensing system 23 is imaged by an imaging lens 24, and is focused on secondary light sources la', 1b', lc', . . . of semiconductor lasers.
form.

These light source images are arranged on a straight line at the same pitch.
A field lens 25 is disposed near this secondary light source, and the directivity of the light east of the secondary light source 1 from 1b', lc', . . . is matched with the collimator lens 26. Therefore, by disposing this field lens 25, the effective diameter of the collimator lens 26 can be reduced by 4.
The parallel light from the collimator lens 26 is deflected and scanned by a galvano mirror 27 driven by a galvanometer 28, and then imaged onto a scanning surface 30 by a scanning imaging lens 29. Therefore, these secondary light sources la', lb', . . . and the three scanning surfaces are provided at optically conjugate positions. As the galvanometer mirror vibrates, the image 31 of the secondary light source moves in the direction of arrow A, while the scanning surface 3 moves in the direction of arrow A2, resulting in two-dimensional scanning. The light collection system 23
was an anamorphic optical system, but when a spherical optical system is used as a condensing system, the secondary light sources la', lb' . ... becomes an ellipse.

Therefore, in such a case, by providing a slit 32 perpendicular to the secondary light source of the optical system shown in FIG. 7 and blocking a part of the light east in the longitudinal direction of the light east cross section, Shapes can be reshaped. Next, a specific example of the Hishi Nao according to the present invention will be described.

When using a light emitting part with a shape of 2 touch x 75 touch, output of 0.75 W, wavelength of 0.89 mm, duty cycle of 5%, and maximum repetition frequency of IM, the material to be used for this laser is A thin layer of Bi (500 Å) was formed on one side of a polyester film having a thickness of 75 μm, and a thin layer of WS (500 Å) was further formed thereon to form a recording layer. It is a highly sensitive heat mode sensitive material of this type. On the other hand, an optical waveguide having a cross section with a thickness of about 2 peaks and 16 peaks in the longitudinal direction is optically connected to the Nakashi laser light emitting section. An optical system that condenses the diverging light from the light output end of the optical waveguide in the longitudinal direction and doubles the width in the transverse direction condenses the light into a four-fold spot on the photosensitive material surface. When irradiated, the laser power that reached the surface of the photosensitive material was approximately 3 hW, and it was possible to record 2〃◇ holes with an irradiation time of 30 ratio Sec. In this case, the repetition frequency of the laser is 167 KHz due to the duty cycle limit of 5%, and if the efficiency of the galvanometer is also 50%, the frequency of the galvanometer is approximately 4 plates z The feeding speed of the sensitive material is 0.0825 side/ In sec, the vertical wisteria dot pitch is 2mm, the number of picture elements on one vertical line is 2100 dots,
Assuming 2970 lines in the vertical direction, 79 lines are recorded on this one page.
Gizzarded.

When such a semiconductor laser and optical waveguide assembly is used, and the number of integrated lasers and waveguides is six, the frequency of the galver is reversed and the feeding speed of the sensitive material is increased six times. It is possible to record with 12.9 sand. By using an optical stack that further doubles the number of semiconductor lasers and optical waveguides, 1
The page recording speed can be approximately 6 seconds. Furthermore, by standardizing the scanner for discussion and recording, the efficiency of the scanner can be improved from 50% to 80%, which further speeds up the recording time for one page to 4 seconds or less.

The above case corresponds to micro-recording that is reduced to 1/48 of A4 size. That is, 4...1 page is microfilmed in 4 seconds. If the degree of integration is increased, it will be possible to record several pages per second, making it possible to use it as a COM.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the apparatus according to the present invention, FIG. 2 is a front view of the scanning plane of the apparatus shown in FIG. 1, and FIG.
B and C are diagrams showing the relationship between the optical waveguide and the substrate used in the Hishitaka device according to the present invention, and FIGS. 4, 5, and 6 show examples of the optical waveguide used in the device according to the present invention. 7 is a diagram showing another embodiment of the device according to the present invention, FIG. 8 is a diagram for explaining an anamorphic optical system used in the device according to the present invention, and FIGS. 9 and 10. and FIG. 11 are views showing an anamorphic optical system used directly in a bag according to the present invention, and FIG. 12 is a view showing an example of shaping the cross-sectional shape of light emitted from a semiconductor laser. 1... Semiconductor laser, 2... Optical waveguide, 5...
Collimator lens, 7... Galvano mirror, 8...
- Scanning imaging lens, 9...scanning surface, 11...scanning spot. Tsutomu/Figure *2 Figure Hitoshi Zuren I Zuwan; Zuren 5 Shio 7 Figure 8 Festival? Zukan/ozusai〃zuhakama'2

Claims (1)

[Claims] 1. A light source section having a plurality of semiconductor lasers, a spherical condensing optical system that images the plurality of light beams from the light source section, and a spherical condensing optical system disposed near the imaging surface of the spherical condensing optical system. It has an image shaping means for shaping an image of the light source part formed by the image shaping system, and an imaging optical system for forming the image of the light source part shaped by the image shaping means on a recording surface, and has a plurality of beam spots. A recording device that uses multiple semiconductor lasers and is characterized by recording on a recording surface.